It was a second stage victory in this year's race for the American from the Garmin-Transitions team as he prevailed by a comfortable distance from Liquigas-Doimo rider Fabio Sabatini at the end of the second longest stage of this year's race.
The 230km route from Avellino, that went right across the Italian peninsula from the west to the east coast, concluded with a twisty final kilometre which saw Farrar's team-mate Julian Dean produce a perfect lead-out.
Such was the distance back to the rest of the sprinters that New Zealand's Dean finished the stage in third position.
The success of Farrar, who also claimed the second stage, leaves home riders still without a single non-team stage win so far this year.
Britain's Charlie Wegelius of Omega Pharma-Lotto along with Italy's Dario Cataldo (Quick Step) and Frenchman Hubert Dupont AG2R La Mondiale) attacked early and opened up an eight minute lead.
But the flat route, with just one category three climb to Valico dell'Imbandina after 92km, allowed the sprinters' teams to keep the gap to a manageable size and the escape trio were caught with 16km remaining to set up a sprint finish.
Astana's Alexandre Vinokourov kept the overall lead, still one minute 12 seconds ahead of world champion Cadel Evans, with no changes amongst the top men on general classification.
Wednesday's 11th stage is a 262km trip from Lucera to l'Aquila, the central city worst hit by a devastating earthquake last year.
"If there is a chance to gain some seconds I will try in Aquila," Kazakhstan's Vinokourov, who returned from a doping ban last year, said..
"It's really tough, we expect very difficult stages on Saturday and Sunday (in the mountains)."
The three-week race finishes on May 30 in Verona.
Result: 1. Tyler Farrar (US / Garmin) 5hrs 49mins 14secs; 2. Fabio Sabatini (Italy / Liquigas) ST; 3. Julian Dean (New Zealand / Garmin); 4. Robbie McEwen (Australia / Katusha); 5. Robert Foerster (Germany / Milram); 6. Sebastien Hinault (France / AG2R); 7. Andre Greipel (Germany / HTC - Columbia); 8. Danilo Hondo (Germany / Lampre)
Standings: 1. Alexandre Vinokourov (Kazakhstan / Astana) 38hrs 59mins 00secs; 2. Cadel Evans (Australia / BMC Racing) +1:12; 3. Vincenzo Nibali (Italy / Liquigas) +1:33; 4. Ivan Basso (Italy / Liquigas) +1:51; 5. Marco Pinotti (Italy / HTC - Columbia) +2:17; 6. Richie Porte (Australia / Saxo Bank) +2:26; 7. Vladimir Karpets (Russia / Katusha) +2:34; 8. Stefano Garzelli (Italy / Acqua & Sapone) +2:47
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