The method of kideny cell-PHA (phytohemagglutinin)culture in vitro for thestudy of fish chromosomes was reported by Yamamoto, K. and Y. Ojima (1973). Inthis paper a new method for inducing fish chromosomes divisions is proposed. The PHAadministration was by pericardial cavity injection in vivo, instead of adding it into thecell culture medium in vitro. The injection does of PHA is 8-10μg/g (body weight),the injection position is better located at the base of pectoral fin, the time for responseneeds about 4-4.5 hours after injection. It needs only 7 hours to obtain a largenumbers of mitotic metaphase figures of kidney cell. About 30 species of teleost fisheswere examined in the experiments. e. g. Parabramis pekinensis, Megalobrama hof-fmanni, Barbodes denticulatus, Cirrhinus molitorella, Clarias fuscus, Monopterusalbus, Anguilla japonica, Ophicephalus argus, Tilapia mossambica etc. all givingsatisfactory results. The average percentage of mitotic division by PHA injectionmethod is 1.56 times than that of the kidney cell-PHA culture; 1.82 times of theblood-PHA culture and 4.51 times of the usual air-drying, reaching 9.86%. Thismethod has a double advantage being rapid and simple, and also adaptable to thefield work.