Abstract <p>We consider long-term measurements of the scattering parameters of radio emission of pulsars B1133+16 and B1137+25 at a frequency of 111 MHz. The observations were carried out with the Large Phased Array (LPA) at the Pushchino Radio Astronomy Observatory of the Lebedev Physical Institute. Pulsars B1133+16 and B1237+25 were observed for 810 and 552 days, respectively. We analyze the dynamic spectra, from which the following parameters and their time variations were measured: the time and frequency scales of diffractive scintillations, the signal amplitude, and the Faraday rotation period (for PSR B1133+16). For both pulsars, rapid variations in the signal amplitude on a scale of 1−3 days were observed. They are mainly caused by refractive scintillations. For PSR B1133+16, variations on a scale of 50−100 days were observed. Among them, the most pronounced are frequency variations in the decorrelation bandwidth over time. Apparently, they are also caused by refractive scintillations on spatial scales of (3−6) × 10¹⁴ cm. For all of the parameters analyzed, modulation indices were measured. For both pulsars, the modulation indices of the peak flux density significantly exceed the estimates obtained with theoretical models. A significant anticorrelation has been found between variations in the peak flux density of PSR B1237+25 and in the decorrelation bandwidth: the correlation coefficient is –0.59. For PSR B1133+16, no correlation is observed. From the behavior of fluctuations in the relative flux density over time and from the variability of the decorrelation band width for pulsar B1237+25, extreme scattering events (ESEs) were revealed. Regular components were found in the structure function of the time variations of the decorrelation band for pulsar B1133+16, which can be interpreted as an indication of regular structures of interstellar plasma inhomogeneities on spatial scales of about three astronomical units.</p>