Self-assembly of H*- and J-aggregates of an indotricarbocyanine dye in phosphate buffered saline was investigated. At pH value of 7.0 the dye studied was shown to form non-luminescent H*-aggregates with the absorption band peaked at 516 nm, its FWHM being 35 nm (1303 cm-1), whereas, J-aggregates are absent. At pH value of 7.4 the H*-aggregates are not formed, whereas, the J-aggregates are observed. The absorption band of the J-aggregates is peaked at 777 nm, its FWHM being 30 nm (497 cm-1). Photoluminescence quantum yield of the J-aggregates does not exceed 10-6. An increase in the solution temperature from 20 to 31oC results in a 25-fold decrease in the self-assembly time of the H*-aggregates. An increase in the solution temperature from 20 to 80oC is followed by a reversible decay of both the H*- and J-aggregates. The H*-aggregate (J-aggregate) absorption band is reduced two-fold at the solution temperature of 37oC (32oC). Thansitions of the dye aggregates to high-lying electronic excited states were evidenced in the steady-state absorption in the spectral range between 400 and 480 nm.