The biology of Cenopalpus irani Dosse, 1971 (Acari: Tenuipalpidae) was studied in 2003 on apple (Malus domestica Borkh.) trees in an orchard at Mahdasht region of Karaj, Iran, and under laboratory conditions at 32±1ºC, 52±3% R.H. and a 16L: 8D photoperiod. Overwintering females began their activities near the end of April and completed three generations per year. The mean time for development from egg to egg in the laboratory was 26.1±0.3 and 19.1±0.5 days for females and males, respectively. The average preoviposition, oviposition and postoviposition periods were 4.5±0.3, 4.1±0.3 and 2.0±0.2 days, respectively.