A series of chlorin p6 derivatives modified at the 3- position of the macrocycle were prepared on the base of purpurin 18. The chlorins obtained have intense absorption maxima in the range of 665 - 698 nm and posses good water- solubility. Studying photodynamic activity of these sensitizers in vitro showed that the most effective was 3- devinyl-3-formylchlorin p6. This sensitizer demonstrated also enhanced in vivo affinity to the tumor tissue in comparison to other chlorins, which correlated with the pH values of aqueous solutions of sensitizers studied.