Pachytene chromosomes ofSolanum nodiflorumJacq. (n= 12) a diploid form ofSolanum nigrumcomplex was studied. An idiogram was constructed showing chromosome lengths, lengths of chromatic and achromatic segments and arm ratio. The twelve chromosomes were readily distinguished on these criteria and described. Chromosome twelve has the nucleolus organizer in the short arm. The idiogram was compared with that of the Indian diploidS. nigrumL.