We characterized three A-type cyclins from tomato: SlCycA1 (AJ243451), SlCycA2 (AJ243452), and SlCycA3 (AJ243453). All of them had the typical cyclin box and LVEVxEEY motif, and were homologous to other A-type cyclins. SlCycA1 and SlCycA2 were significantly expressed in meristematic tissues, but the transcript of SlCycA3 maintains relatively low levels in the various tissues we tested. To investigate the effect of various hormones on the expression level of A-type cyclins, two-week-old tomato seedlings were treated with $10;{mu}M$ indole-3-acetic acid (IAA), 3-Indolebutyric acid (IBA), or $alpha$-naphthalene acetic acid (NAA) for 0, 0.5, 1, 2, 5, or 10 d. Treatment with IAA or IBA significantly increased the cells in the G2 phase after treatment for 10 days, whereas the proportion of cells in the S phase was strongly increased by NAA treatment. RT-PCR analysis showed that the SlCycA1 and SlCycA2 transcripts accumulated at 5 days and 2 days after IAA treatment, respectively. Also, the SlCycA3 transcripts were strongly induced after 10 days of IBA or NAA treatment. These data provide new insights into the cell division accompanying hormone treatment in tomato.